const colorPicker = document.getElementById('color-picker');
const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

function init(){
    const w=500,h=300;
    canvas.width=w*devicePixelRatio;
    canvas.height=h*devicePixelRatio;
    canvas.style.width=`${w}px`;
    canvas.style.height=`${h}px`;
}